A subsidy extension is likely, but firms face choices. One survey finds that the percentage of laid-off employees opting for COBRA has doubled compared with the months immediately prior to enactment of the subsidy.

Congress appears likely to extend a February law that subsidizes COBRA health care premiums for laid-off employees, allowing hundreds of thousands of beneficiaries to retain affordable coverage but creating new administrative headaches for employers.

Under that subsidy, embedded in the American Recovery and Reinvestment Act of 2009, the federal government pays 65 percent of COBRA premiums for COBRA-eligible employees who are involuntarily terminated between September 1, 2008, and December 31, 2009. The subsidy is available for nine months or until an enrollee is eligible for new group health insurance coverage.

At the time the COBRA subsidy legislation was passed, the Joint Committee on Taxation estimated that the subsidy would cost the federal government about $25 billion and benefit about 7 million jobless individuals and their families.

But for many beneficiaries, that subsidy has come to an end. The subsidy expired at the end of November for beneficiaries who have received the nine-month subsidy since it first became available, which generally was March 1.

As a result, in December billing statements some employers and plan administrators have asked beneficiaries to pay the full COBRA premium, instead of 35 percent.

“We have already set up a 100 percent billing for December,” said Kathy Dupree, benefits manager at Core Laboratories, a Houston-based company that provides services to petroleum companies.

But some plan administrators—especially those that send out payment booklets for COBRA beneficiaries—say that for now they are not sending out new booklets asking beneficiaries to pay the full premium.

Anderson said that if Congress does not extend the subsidy, the work involved in obtaining the money owed by beneficiaries who underpaid the premium would be less than issuing refund checks and adjusting future COBRA premiums as an offset to overpayments if Congress does extend the subsidy.

Benefits experts say it is likely Congress will extend the subsidy, most likely as part of a broader bill, though probably not until mid- to late December.

In fact, the chief reason Congress hasn’t acted is that members have been consumed with the effort to pass comprehensive health care reform legislation, observers say.

Less certain, though, is the shape of the extension legislation.

“There is little doubt that Congress will extend the subsidy. But no one knows exactly how the law will be extended,” said Andy Anderson, a partner with Morgan, Lewis & Bockius in Chicago

For example, one possible course of action would be for legislators to make the subsidy available for those who lose their jobs after December 31, 2009.

Another possible course of congressional action would be to extend the premium subsidy for current beneficiaries for several months and to make the subsidy available for those who lose their jobs during the first half of next year. Bills have been introduced in the Senate and the House that would do that, though no action has been taken on those measures.

Regardless of which approach Congress takes, employers and plan administrators will have more work ahead of them in communicating the changes to beneficiaries.

Still, assuming Congress extends the subsidy, the amount of work will be far less compared with earlier this year when the subsidy legislation was enacted. At that time employers, with no regulatory guidance, had to locate former employees who terminated employment as early as September 1, 2008, and initially declined COBRA and give them a second chance to enroll.